X-ray, Optical and Radio Images of Abell 3376
These images of the galaxy cluster Abell 3376 are from Chandra and ROSAT X-ray data (gold), an optical image from the Digitized Sky Survey (red, green and blue), and a radio image from the VLA (blue).(Credit: X-ray (NASA/CXC/SAO/A. Vikhlinin; ROSAT), Optical (DSS), Radio (NSF/NRAO/VLA/IUCAA/J.Bagchi))

Simulation Showing Structures Growing with Cosmic Time
These are three snapshots taken from a simulation by J.Diemand, J.Stadel
and B.Moore showing the formation of cosmic structure in the presence of
dark matter and dark energy. The snapshots are taken at times when the
Universe was 20%, 60% and 100% of its full size (for ease of comparison,
the images have been scaled to be the same size). Note how structures
increase in size under the attractive force of gravity, leading to the
formation of the largest collapsed structures, galaxy clusters. The growth
of galaxy clusters is controlled by the competing effects of dark matter
(causing objects to shrink under gravity) and dark energy (causing
accelerated expansion) and by the properties of gravity over large scales.(Credit: J.Diemand et al.)